Health Short: Endless days of work may be hard on the heart

Working long hours may increase the risk for atrial fibrillation, or irregular heartbeats that can lead to serious cardiovascular complications, a new study in The European Heart Journal found.

Lengthy work hours have been shown in several previous studies to increase the risk for cardiovascular disease.

The researchers began with 85,494 men and women from Britain, Denmark, Sweden and Finland with no record of atrial fibrillation. They assessed working hours at the start, and then followed them for an average of 10 years, defining incidents of atrial fibrillation with medical records and death certificates.

They adjusted for many variables — sex, socioeconomic status, obesity, smoking, alcohol use, respiratory disease, diabetes, high blood pressure, depression and others — and found that the more hours people put in, the greater their risk. Compared with people who worked 35 to 40 hours a week, those who worked more than 55 hours had a 40 percent increased risk of atrial fibrillation.

The study wasn’t without its limitations. Researchers assessed working hours only once among the participants, and the experiment did not account for job type or shift work. Also, there are many other factors that contribute to the risk for atrial fibrillation.

Still, the lead author, Mika Kivimaki, an epidemiologist at University College London, said that “the relative risk of AF associated with long working hours is of similar size as those associated with hypertension, diabetes, obesity and heart failure.”